The present disclosure generally related to pyrocatalytic coatings, and more particularly, pyrocatalytic coatings that include a metal oxide crystalline catalyst material for improved cleanability of heating device surfaces.
Heating devices such as ovens, irons, and cooking surfaces, are often covered with a hard and resistant layer so that foodstuffs, starch, dirt, and the like that can build up on surfaces of these devices during use can be readily cleaned. For example, the walls of an oven are often coated with a smooth enamel coating so that foodstuffs do not permanently adhere to the surface and to permit ashing thereof when the oven is in a self-cleaning mode. Self-cleaning modes for current surface finishes generally require exposing the oven interior to temperatures in excess of 850° F. to completely ash the attached foodstuffs, thereby permitting the end user to wipe away the resulting ash from the surface. Because of the high temperatures used during the self-cleaning mode, a significant amount of thermal insulation about the oven interior is required to prevent damage to delicate electronics. For example, wiring currently used to operate the oven typically requires special high-temperature insulation, which represents additional overhead in the manufacture of the oven. To reduce the cost associated with the insulation and enable design changes within the oven chamber, it is desirable to reduce the self-cleaning temperatures. A lower temperature self-cleaning cycle may allow use of conventional insulation in wiring, latches, door construction, fans, and the like, thereby reducing the overall cost and enabling additional product enhancement.
Previous attempts to lower the self-cleaning temperatures have included the use of porcelain enamel coatings that include a fluorocarbon polymer component and an enamel-forming component with the enameled forming component including a lead- and cadmium-free glass frit. However, cleaning cycles using these materials require application of water and/or moisture to be efficient. Other types of coatings included multiple glass frit and catalytic single metal cation oxides, where the metal cation is generally a transition metal selected from elements in periods 4, 5 and 6 of the periodic table or components with low staining properties. In addition, non-oxide coatings deposited by chemical- or plasma vapor deposition have been disclosed. These coatings are generally ineffective at reducing the pyrolysis conditions required for the complete combustion that is desirable for self-cleaning modes used in oven designs.
Accordingly, there is a desire to reduce the pyrolytic conditions for surfaces used in heating devices so as to improve cleanability as well as reduce costs associated with current heating device design, e.g., reduce insulation.